Thoughts on the HUD type GPS activated Speed display.

[gordon_s1942]

A few weeks ago I purchased a Polaris brand GPS activated Speed display and its taken me awhile to locate it and the display film on the windscreen to suit me.
Firstly I have to say how sensitive the unit is to pick up the available satellites as I have a 3 car size corrugated tin shed and parked nose in, it takes maybe 2~3 minutes after the key is turned on for it to display the time.
I also have a GoCruise GPS and theres no way it will show 'Satellite Lock' until the car is outside the shed completely.
Both the GoCruise and the HUD display antenna are within inches of each other, maybe the HUD display with its separate antenna is more sensitive then the GoCruise inbuilt one.

So far I have found the brightness of the reflection most of the time when driving directly into low angle morning and afternoon Sun to be adequate to read it.
It has a variable brilliance level which I have set on 'Auto' and I noted as I drive into the shed, it reduces the brightness of the display accordingly.
I currently have the reflective film roughly where the Rego sticker used to go but on my side of the windscreen where I can easily see it but its not in the 'direct line of sight'.
One thing I dont understand is why that most of these devises allow you to calibrate it to match the Cars speedo because I wanted it to give the actual speed of the Car at that time which I thought was more important than what the speedo is reading.